The present invention broadly relates to continuous casting and, more specifically, pertains to a new and improved apparatus for closing or obturating the sides of a mold chamber of substantially rectangular cross-section in a continuous casting installation.
Generally speaking, the apparatus of the present invention obturates the sides of a mold chamber which comprises two arcuate cooled broad or wide side walls rotating in the direction of casting or the direction in which the cast strand moves and two stationary cooled narrow side walls. The two stationary cooled narrow side walls engage between the two arcuate cooled broad side walls.
In the continuous casting of metals, in particular of steel, in the form of thin broad strips, high casting rates are necessary to achieve the production capacities required in large-scale industrial operations. Furthermore, considerable difficulties arise in achieving uniformity in the feeding of the molten metal into a broad, thin, oscillating, open-ended mold in which the metal solidifies at least at its surface. To solve these problems, continuous casting installations have been developed in which the molten metal is brought between two cooled rotating drums or moving strips, or a combination of both, and is allowed to solidify while in contact with the cooled walls of these elements. In such installations, the cooled walls, which form the narrow sides of the mold chamber, may be moved in synchronism with the drums or strips or be kept stationary.
German Patent Publication No. 2,063,591, published July 15, 1971, discloses a strip-casting machine comprising two drums which rotate in the direction in which the cast strand is moved. The two arcuate and cooled surfaces of the drums form broad side walls of the mold chamber, while two stationary cooled walls constitute the narrow side walls of the mold chamber. These narrow side walls engage to some extent within the two arcuate broad side walls. In the direction in which the strand moves, the engaging portions of the narrow side walls are directly adjacent a metal feed device and can be electrically heated. In this continuous casting installation, solidification at the narrow sides of a strip or thin slab is delayed over part of the thickness of the strand, which can result in metal breakouts downstream of the narrowest gap between the two drums or at the outlet of the mold chamber. Furthermore, solidified portions of the strand crust or shell can become jammed between the engaging portion of the narrow side wall and the mold chamber which narrows in the direction of movement of the strand, and these portions of strand crust or shell can tear open an already solidified thin strand crust at the broad sides of the strand and lead to defective strands or even metal breakouts.